Stringing pianos



(No Model.)

0. S. WEBER. STRINGING PIANOS.

No. 510,944. Patented Dec. 19, 1893.

Ciaried 772:569': f

UNITED STATES PATENT OFFICE.

CHARLES S. \VEBER, OF SAN JOSE, CALIFORNIA.

STRINGING PIANOS.

SPECIFICATION forming part of Letters Patent No. 510,944, dated December19, 1893.

Application filed November 5, 1392- Serial No. 451,071. (No model.)

T0 at whom it may concern:

Be it known that 1, CHARLES S. WEBER, a citizen of the United States,residing at San Jose, in the county of Santa Clara, State of California,have invented certain new and useful Improvements in Stringing MusicalInstruments; and I do hereby declare the following to be a full, clear,and exact description of the invention, such as will enable othersskilled in the art to which it appertains to make and use the same.

Figure 1 is a front view of the soundboard and stringing frame of anupright piano showing the application of my invention. Fig. 2 is adetail side view showing the relative arrangement of the string, theframe, sound board, dampers and (tone refiner) equalizer agraffe. Fig. 3is a side view ofa testing apparatus for showing the application andproving the theory of the invention.

This invention relates to stringing musical instruments, especiallypianos of that class in which certain proportions of length areestablished between the two sections of string lying next tobut onopposite sides ofthe bridge over the sound-board.

The object of this invention is to gain vibratory power in theinstrument and so regulating those proportions, that in the said twosections of every string the maximum intensity of sympathetic influenceshould appear at the point where the tension is equal in both sections.To attain this end two seemingly insignificant factors are hereconsidered which heretofore have not been accorded any influence indetermining the proper relation of those sections. The factors referredto are the diameter of the string and the rigidity of the material inthe same. To ascertain the value of these factors I use the followingdevice which admits of great accuracy without requiring elaboratepreparation. The string is stretched between two metal bridges, shapedas shown under A and D inFig. 3 to allow an exact measurement of theclear length between them. Six or eight feet of this admits of correctresults being obtained. At the point of contact with a bridge the stringis deflected as shown before it reaches its point of fastening. Thedistance of the string from a parallel soundboard is one-half inch. Asteel rod L one half inch square and about six inches long is placedcrosswise to the string between this and the soundboard. A duplicate Lofthe first bar is placed above the string. Being set with the edgesperfectly even and connected by means of screws the two bars L and Lform a clamp by the aid of which the string can be held at any distancebetween the bridges and divided into two sections of equal tension. Bydint of trial the point is now ascertained at which one section soundsexactly the octave of the other. \Vere the rule correct that serves forcalculating the proportional lengths in inventions of this class, thensaid point would be where one section has exactly double the length ofthe other. This, however, is not the case in any string having a uniformthickness. By subtracting the length of the prime 0 D from double thelength of the octave A B there remains a difference which augments withthe diameter of the string and with the rigidity of the material ofwhich thestring is composed. This difference in length will be calledhere the equivalent of rigidity. In the various sizes of ordinary pianowire (steel) I found it so nearly equal to five diameters of the stringthat no appreciable error will be committed by taking the equivalent ofrigidity equal to live diameters in all calculations relating to lengthsin the ordinary piano wire.

To simplify the following explanation, that section of string which in apiano receives the blow of the hammer is called here the tone section,its prolongation beyond the bridge of the soundboard being named thehitch section. A B in Figs. 1 and 2 shows the former; G D the latter.The lengths of the tone section remain in this improved con structionthe same as those used in ordinary pianos. The difference is in thehitch section. 'lo find the proper length of this for a given note ofthe piano, the equivalent of rigidity (in the proper string) is firstsubtracted from the length of the tone section.

in an excessive length of hitch sectiom-thendivision is resorted tounder identical conditions, that is, a number is selected as adivisorwhich will produce as aquotie'nt a length which being added to and theequiva-- lent of rigidity will result in the greatest length possiblefor the available space in which to string the hitch section. Thefollowing examples will serve to illustrate this rule:

Supposing we find in a .piano. dimensions as follows: limit -for thecombined =length.of

both sections, forty-eight inches; lengthiof. tone sectiomthirtytwoinches; diameter of; string, 0.04 inch,making theequivalentlofrig- 1TIf-Mfi} idity (in common piano wire) 02inch. should choose 2as a,divisor in calculatingthe lengthof .the -:hitch section, the resultwould exceed the limit by 0.1 inch. Thus 3 must be the divisor toexactly conform to the, rules, making the lengthof the'hitc'h section 1'section,.sometimes touching the ilin'eof ex- 10.8 inches.

Ina second example we put the lengthofi the .lJOIlG section;at'1 2;1inches, the other data being unchanged. If ,we :now should choose 2 as amultiplienwe would not obtain-the greatest length admissible for thehitch sec-E tion, asthere isexactly room for a:le.ngthre-' sulting from.3 vas a multiplier, giving the" those notesw-here.bothsections areequal, the

If these rules be applied to all the plain stringsiof a piano,thefollowing series of proportions .iwillreslt 'in-the lengths of thetwohitch section 35.9-inches.

sections:

1: 1 l: 1 1 :i(2;1r) h '1: (3-2r) 15 g '1: (43r) and 1: 1 1: (5-40) 191;.(6 5?) 13 the .unit of measure (equal to one) in every string. '4"stands for equivalent of rigidity. Bothseries start with those notes inwhich .1

the .two sections are of equal length. The first series givestheproportional lengths en-; countered in ascending from the ll liddle tothe highest notes, the "second -those' encountered in descending fromthe middle notes until thecovered (low bass) strings are reached whichby reason of variations in heir diameter cannot form similarproportions.

Above proportional lengths correspond in exactly the same order to thefollowing proportional numbers of vibration:

The number of vibrations corresponding to the tone sectionprecedesthesign inevery ,proportion. The correctness def this relationbetween lengths and numbers of vibra ;tion;can b9 provenbymean-sot'itheapparatus :used to ascertain the :equivalen-tfof rigidity.

Similar proportions are shown in ;Fig.:2 the equivalent of rigidity :beiv ,t s fl a v 10.51 n

jin; the drawings.

A :Bshow the tone section decreasing from .the lower toithe highestnotes as list-1315111 al-l constructions.

O D show the varying lengths vlof =the hi-tch :treme limit Z Z at othertimes .somevehatoff {from this. I

:Below .the vsquare representing .theou tside' dimensions of the .pianoisai-li-ne yy divided ;into seven parts,'each-of whichshows how far acertain octave extends in the instrument.

It will be-seen that, with the exception of ';by the two sections ofevery string. Thisre- =lation between lengths and vibrationsconstitutesani-important feature of this invention and in partdistinguishes-it' from others in which proportional lengths are shownbearing an inverse relation to their corresponding'numbers of vibration.

In sounding a note regulated according to the'rules here laid down notonly the tonesection but the corresponding hitch section also willvibrate; the latter moved by the sympathetic influence of-theformeryif'thetension be equalinboth sections; butthe slight- 1' :stdifference in-tensionwill causea marked iminution in theiintensit ofs math ot'c vr The length of the tone section is taken as y y p d brations.This circumstance I take advantage of for ascertaining thepoi-nt-at-which the tension-is equal in both sections. This equality isalwaysdisturbed by the-frictional resistance which the string encountersin being drawn acrossthe bridge of-=the soundboard. To correct this Iprovide the hitch section with the equalizer agralfe and: an

extra set of dampers. The first will be fully described and claimed in asubsequent application for Letters Patent as a device admitting of avery delicate graduation in the tension of a string. The graduation iseffected by the turns of the regulator screw N in Fig. 2. As for theextra dampers they are combined with a mechanism allowing them to acteither in concert with or independently of the ordinary damperspertaining to the tone section.

To equalize the tension in any string I first set its extra damper so itremains open after the stroke of the hammer as shown in F, Fig. 2,whilethe ordinary damper closes as shown in E to leave only the sympatheticvibrations. By repeatedly striking the proper key and turning gently atthe corresponding regulator screw a gradual increase isperceived in theintensity of the sympathetic vibrations if the turns be in the rightdirection. Stopping at the point of maximum intensity, perfect equalityis obtained in the tension of both sections even without the aid of aspecially trained ear. To rectify any possible mistake both dampers arenow set to act in concert, and are kept open long enough after eachstroke to ascertain the nature of the tone interval formed in the twosections. This must be the prime in every string where the tone sectionis the shortest, the same where both sections are of equal length. Therethe hitch section is the shortest its vibrations inust form acertainovertone, the distance of which from the prime of the tone section isdetermined by the proportions of length prevailing between the twosections. Whatever be that distance the correctness of the interval isreadily recognized by a trained car even when its upper note does notbelong to any scale of the piano, as is the case where the proportion ofvibrations is one to seven or one to eleven. Having thus obtainedequality of tension coincident with the maximum intensity of sympatheticinfluence the object of this invention is accomplished. The follow ingcomparison will show that this result could not be obtained by means ofproportional lengths in which the diameter of the string is not afactor. Taking the following dimensions: limit for the combined lengthof the two sections, forty-two inches; length of tone section,thirty-two inches; thickness of string (piano wire), 0.04 inch, theequivalent of rigidity being 0.2 inch; the length of the hitch sectionwill be 8.15 inches according to rules of this improvement, while theordinary calculation would assign eight inches to the same section whichby equal tension with the tone section would sound a note one-third of asemi tone above the fifteenth (second 00- tave) of the tone section, aninterval which will prevent all sympathy between the two sections. it onthe other hand we establish sympathy by so reducing the tension of thehitch section that notwithstanding its insufiicient length it will soundthe fifteenth to the prime of the tone section, than we have destroyedthe equality of tension, throwingthus a certain pressure on the bridgeof the sound board. In the example here given that pressure would not beless than three pounds which may be accepted as a low average for allplain strings except those in which both sections are equal. Thus in anupright piano of ordinary size not less than thirty strings below andabout one hundred strings above the middle notes would throwconsiderable pressure on the bridge; the bass strings upward and thetreble strings downward. To prevent the bridge thus being displaced itwould have to be made even stronger than where only a short length isleft beyond the bridge, just sufficient for fastening the string as inthe ordinary construction, while in this improved construction where thebridge is perfectly balanced all the attention hitherto paid to itssolidity can be henceforth turned to its vibratory quality.

Anotheradvantage which this improvement possesses over similarconstructions is that it applies the law of sympathy to all the plainstrings of the piano, combining in the same instru ment the brilliancyderivable from overtones with the surprising length and fullness of toneobtained where two or more lengths in the prolongation sound the primeto the main string. To prevent an under tone being formed in this case Iplace the point of nodal damper against the hitch section at a distancefrom either end equal to the length of the tone section diminished byhalf the equivalent of rigidity.

Having thus described my invention, what I claim, and desire to secureby Letters Patent, is-

l. A pianoforte or other stringed musical instrument having a bridge,strung by having the musical string extended on opposite sides of saidbridge to form a tone and a hitch section, the latter sounding bysympathetic action, and varying from a proportional length of the tonesection by a length corresponding with about five times the diameter ofthe said string, substantially as described.

2. A pianoforte or other musical instrument having abridge, strung byhaving the musical string extended on opposite sides of the said bridgeto form a tone and ahitch section, the latter sounding by sympatheticaction, and varying from a proportional length of the tone section byabout five times the diameter of the said string, and having the saidtone and hitch sections of equal or like tension, substantially as andfor the purpose described.

3. A stringed musical instrument havinga musical string divided into atone and a hitch section, and having a "tuning device applied to thesaid hitch section to vary the tension thereof without altering thetension of the tone section, substantially as described.

4;. The combination with a musical string composing a musical hitch anda tone section of proper proportional length, of separate andindependent dampers for the two sections of the saidstring,substantially as described. to

In testimony whereof I affix my signature in presence of two witnesses.

CHARLES S. WEBER. Witnesses:

WM. E. BOON, O. J. 'BROODDIES.

